What are the conditions for lawful reception of Communion?
To receive the sacrament of Communion worthily one must be a baptized Catholic in the state of grace and believe what the Church teaches about this sacrament. One conscious of having committed a mortal sin must make a sacramental confession before approaching the sacrament. One must also receive Communion with an upright intention, for example, out of love for Christ or in a desire to grow in grace and in unity with all His Mystical Body. One should not receive Communion simply because others are receiving it. The Church also directs us to abstain from food and drink (except for water and medicine) for at least one hour before Communion.
If one who has sinned gravely has a pressing need to receive the Eucharist and has no opportunity to confess, one should first make an act of perfect contrition, an act which includes in it a promise to confess as soon as possible. One who deliberately received Communion while in a state of mortal sin would commit a grave sin of sacrilege.
“Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord” (1 Cor. 11.27).
Reception of the Eucharist together signifies unity in faith and union with one another in the family of faith. Catholics and non-Catholic Christians are regrettably separated in many ways. For this reason non-Catholics could not be admitted to Communion in the Catholic Church except in exceptional circumstances. The local Catholic bishop is to pass judgment in each case.